The contribution of nanostructures towards the wing patterning of yellow Catopsilia pomona. How it differs from the lime?

Abstract

Polyphenism, an adaptation to survive throughout the year, is shown by many butterflies including Catopsilia pomona. With the variation of seasons, different morphs were found. Among all the morphs, lime exists throughout the year whereas the yellow one is available only in the winter season. The current study deciphers the colouration mechanism of yellow morph using various microscopic and spectroscopic techniques. The scanning electron microscopy analysis reveals various types of scales on the dorsal as well as the ventral side. The shape of the cover scale varies from region to region. The fine structural arrangement of the scale like window, ridge, microrib, crossrib and pigments vary throughout the wing. The pigment present in the wing is pterin as evidenced from the shape and its isolation technique. Absorption spectroscopy further confirms the presence of various types of pterin within the wing. Scanning electron microscopy discloses the dense amount of pigments within the wing. The fine structural arrangement of the wing of yellow C. pomona is compared with the yellow region of the lime C. pomona. All together, the current study describes the fine structural arrangement of the wing of yellow C. pomona and the various types of pterin which contribute towards the wing colouration. The advantage of yellow morph over lime is also discussed in this paper.